IC cards are widely used in personal computers, video games and other electronic devices. The storage potential of such IC cards has increased more than a hundred times compared to magnetic memories. In addition to memories, IC cards are also used in CPU's.
IC cards have multiple contacts in order to electrically connect them with terminals designed specifically for that purpose.
Special assemblies for IC cards usually comprise an ejector unit, whose purpose is to facilitate removal of the IC card inserted in the terminal, and a connector having contacts matching with those on the IC card. This connector it usually fixed to the printed circuit board of the special assembly for the IC card. The contacts of this connector are joined to the printed circuit board of the special assembly for the IC card, thus forming electrical connection between the IC card and the assembly for the purposes of information transmission.
FIG. 22 represents an exploded perspective view of a conventional ejector unit with a connector, as it is for example known from Japanese Publication No. 91-38772.
Ejector 10 consists of a frame 12 made of a plastic, a plate 14 to be inserted in the plastic frame 12 to which an IC card (not shown in the drawing) is attached, and an ejection device for ejection of the IC card inserted in the frame. The ejection device 16 consists of an operating bar 16a which is depressed when the user has to eject the IC card, spring 16b loading this operating bar 16a, and a cam bar 16c whose one end is connected to the operating bar 16a and the other end is connected to a projection 14a made on the plate 14. In addition, in order to retain the operating bar 16a of the ejection device 16 in the frame 12, a retaining device 12a is provided in the frame. Plate 14 has catches 14b intended for pushing the other end of the IC card during ejection. Thus, the conventional ejector unit consists of many parts, and its manufacturing is a complicated process. Another problem is that the frame is made of a plastic, and for sufficient strength it should be of substantial thickness, thus greatly reducing the possibility for miniaturization.
By connecting this ejector unit 10 to connector 18 and by inserting an IC card with a special connector (not shown in the drawing) attached to it, connection of the IC card to the printed circuit board is accomplished, as is for example shown in Japanese Publication No. 91-38772.
The connector has multiple contacts through which information is exchanged between the IC card and the special terminal for the IC card. These contacts are usually of the male type and are made in the form of a round pin. Therefore, soldering of the terminals to the printed circuit board requires almost the same area as the cross section of the round pins. Since an additional space for an insulating medium is required around the pins, their pitch is rather large.
It is a well known fact that introduction of integrated circuits gave impetus to an increased density of electronic components. IC cards, with integrated circuits as their main elements, are the best example of high density devices. As a result of these developments, IC cards appeared with pins arranged at a narrow pitch in one row. Thus, it became impossible to use connectors having round-type pins arranged at a wide pitch.
A method is known in the art making it possible to reduce the pitch of contacts in connectors by using contacts stamped from a flat metal sheet. These contacts are punched out from a metal sheet, and have surfaces remaining from the original metal sheet, the surfaces being formed in the process of punching. The advantage of these contacts is that they are arranged in a certain pattern in an insulating housing so that the surfaces remaining from the original metal sheet are facing each other, thus allowing for a rather narrow pitch between the contacts. Another advantage is that the contact termination sections are formed without bending and the pitch of their soldered connections is also narrow. An additional advantage is that soldering operations involve surfaces formed in the cutting or punching process which are free from spring forces, thus providing for a good quality of soldered connections, as it is disclosed in Japanese Publication No. 92-14382.
On the other hand, there are IC cards designed for data processing which have even higher density of electronic components. Such cards have contacts arranged in two rows, an upper and a lower row. The contacts stamped from a metal sheet described above are designed for arrangement in one row, however they cannot be used in a two-row arrangement because their termination sections will interfere with each other. Due to this disadvantage, these contacts cannot be used in IC cards that require two rows of contacts.
Connectors having two rows of contacts for use in IC cards, such as those shown in FIGS. 23 and 24, are known in the art, as it is for example described in Japanese Publication No. 86-194971.
In connector 20 shown in FIG. 23, contacts 22, 24 are arranged in pairs, one contact above the other. In order to avoid interference between termination sections 22a, 24a, contacts 22, 24 are bent in opposite directions so that their soldering locations on a printed circuit board (not shown in the Figure) are arranged in a straight line. In connector 30 shown in FIG. 24, contacts 32, 34 are also arranged in pairs, one contact above the other. In order to avoid interference between termination sections 32a, 34a, contacts 32, 34 are bent in such a manner that their soldering locations on a printed circuit board (not shown in the Figure) are arranged in a zig-zag pattern. Attempts were made to use contacts punched out from a metal sheet in the connectors of the type shown in FIGS. 23, 24, but it was necessary to bend the contacts as in the above examples.
In the connectors intended for the use with IC cards having upper and lower rows of contacts, the contacts are usually bent downward.
In connector 20 shown in FIG. 23, termination sections 22a, 24a are arranged in such a manner that they form a single row on the circuit board, and because, in addition to the area occupied by the termination sections, a distance is left between them for insulation purposes, the contact pitch is rather large. This prevents achieving a high density of components arranged on printed circuit boards.
In connector 30 shown in FIG. 24, termination sections 32a, 34a are arranged in a zig-zag pattern which makes it possible to make the contact pitch slightly narrower than in the case of connector 20 shown in FIG. 23. However, this leads to a more complicated pattern on the printed circuit board. In addition, contacts of both connector 20 and connector 30 are made by stamping from a metal sheet, and their termination sections are bent downward. Because of this, residual mechanical stress in the contacts can result in an uneven position of the ends of the termination sections relative to the surface of the soldering connection which ultimately can lead to a defective soldering or undesirable connections between adjacent contacts.
Accordingly, it is an object of the invention to provide an assembly for connecting an IC card to a printed circuit board, the assembly comprising a surface mounted connector with contacts arranged at a narrow pitch in upper and lower rows for connection to cards making it possible to achieve a high density of electronic components and a reliable soldering connection to printed circuit boards. The invention further comprises an ejector unit which is simple in manufacture and, at the same time, has sufficient strength and relatively small dimensions.